I have set up a job to notify our VisualCron administrative staff when things happen on the server that we want to make sure we all know about...such as jobs being deleted or inactivated, the server being set to off, or a trigger expiring.

By narrowing down which VisualCron events are included in which triggers and using a notification that includes which trigger caused the job to run, I have determined that it is apparently "Job Deleted" that is causing the notification to fire when a job misses execution due to a time exception.